- 2004.05.27 07:30 "Re: [Tiff] large TIFF - two alternatives", by Andrey Kiselev
- 2004.05.27 09:25 "Re: [Tiff] large TIFF - two alternatives", by Rob van den Tillaart
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2004.05.27 10:43 "Re: [Tiff] large TIFF - two alternatives", by John Aldridge
- 2004.05.27 12:49 "Re: [Tiff] large TIFF - two alternatives", by Andrey Kiselev
- 2004.05.27 13:05 "Re: [Tiff] large TIFF - two alternatives", by Frank Warmerdam
- 2004.05.27 18:31 "Re: [Tiff] large TIFF - two alternatives", by Chris Cox
- 2004.06.01 11:50 "Re: [Tiff] large TIFF - two alternatives", by John Aldridge
- 2004.05.27 16:37 "Re: [Tiff] large TIFF - two alternatives", by Frank Warmerdam
- 2004.06.04 13:31 "RE: [Tiff] large TIFF - two alternatives", by Ed Grissom
- 2004.06.09 20:33 "[Tiff] Re: large TIFF - two alternatives", by Steve Carlsen
2004.05.27 13:05 "Re: [Tiff] large TIFF - two alternatives", by Frank Warmerdam
This is a serious question, and not intended as a flame: if I need to support a new file format to get >2/4GB support, why wouldn't I just use PNG?
John,
If it works, then by all means.
Some reasons why some folks might not find PNG sufficient:
- I was pretty sure that libpng does not normally use the large file API. If not, most applications won't support large png files.
- PNG does not support the variety of pixel data types that TIFF does (ie. floating point).
- PNG does not support the variety of lossless and lossy compression approaches of TIFF.
- PNG does not have widely accepted mechanisms to embed industry-standard metadata - especially the geospatial information my community embeds in so called GeoTIFFs.
- PNG does not support random access to large files well. My understanding is that PNG image data is libz compressed in one big chunk. This makes it very inefficient to read a small window out of a large file, such as we often do in the mapping world.
In short, there are many features of TIFF that are desirable in specific sorts of imaging applications that are missing in other formats.
All that said, given the "compatibility gap" we are likely to face with any new large file approach I do sometimes wonder if other existing formats which support large files wouldn't be sufficient.
PS. I love PNG and use it extensively for some applications.
Best regards,
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I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent